Nucleopeptides are a class of molecules that contain both nucleobases and amino acids, which have considerable biological and biomedical importance. Naturally occurring nucleopeptides, such as willardiine-containing nucleopeptides and peptidyl nucleosides, are antibiotics. A number of unnatural nucleobase-containing peptides, such as peptide nucleic acids (PNA), have applications in biology and biomedicine (e.g., as analogues of DNA). Such biological significance renders nucleopeptides useful molecules for studying biology.
Hydrogels, which consist of crosslinked matrices and water, have emerged as an important class of biomaterials due to their morphological similarity to extracellular matrices (ECM) in tissues and organs. Although both natural polymers (e.g., collagen, gelatin, hyaluronic acid, and alginate) and synthetic polymers (e.g., poly(D-L-lactide-co-glycolide), poly(N-isopropyl acrylic amide), and poly(ethylene oxide)) can serve as hydrogels in biomedical applications (e.g., tissue engineering and drug delivery), the currently known members of each class have considerable drawbacks or limitations. For example, the separation and purification of natural polymers are non-trivial, and synthetic polymers are largely passive even if they are functionalized.
Supramolecular hydrogels, resulting from molecular self-assembly of nucleopeptides in water, have exhibited considerable promise for applications in biomedicine due to their inherent biocompatibility and biodegradability.
Nanofibers, comprised of self-assembled peptides, that form supramolecular hydrogels have shown considerable promise. These self-assembled peptides have served as scaffolds to guide the differentiation of neuron progenitor cells, media for cell culture, and carriers for drug release. Like modified peptides, derivatives of glycosides can also self-assemble into nanofibers to give supramolecular gels or hydrogels, which has led to the development of semi-wet peptide/protein arrays as biosensors and intelligent soft materials. Recently, nanofibers of deoxynucleic acid (DNA) were found to form supramolecular hydrogels.